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Flowering Hormone

There is increasing evidence to suggest that a flowering hormone exists in plants. This is has been supported by a number of grafting experiments. A short day plant kept in long day conditions can be induced to flower, if a properly photo induced plant is grafted on it. It clearly indicates that a diffusible flowering hormone has moved from one plant to the other and has induced the latter to flower. This hormone has been named florigen but it has so far not been isolated.



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Lysenko (1928) a Russian geneticist found that artificial cold treatment of germinating winter wheat seeds could induce flowering if grown in spring. This process of cold treatment that hastens flowering is called vernalisaion.

process of cold treatment in carrot plats

Technique of Vernalisation

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The seed is first soaked in water and allowed to germinate. It is then given the low temperature treatment for an appropriate period of time, which varies among different varieties from a few days to many weeks. The low temperature range is from 0 - 4o C.

Vernalisation prepares a plant to flower. It makes the plant perceptive to a stimulus but does not function as a stimulus.

If vernalisation is followed by high temperature treatment at about 40o C for a minimum of 2 days, the vernalisation stimulus is lost. This is known as devernalisation.

technique of vernalisation

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